Diesel return line repairs

Back in the old VW diesel days, they had different injectors different years. 110,120 and 130 bar models. They had different pump timing specs for the different ones, till eventually they went with spec for the 120s for all.

Hard starting cold was either glow plug failure, leaky return lines letting air in to lose the prime, or leaky lines anywhere actually. Sometimes the pump seal would wear out and allow air in there while sitting overnight. The test was to park the car nose downhill to get the fuel tank level above the pump level and if it started fine, you were sucking air somewhere.

The pump seal cheap fix was to install an electric feed pump to deliver fuel to the pump for starting. Once running internal pressures would force the seal to seal on the shaft.

Engine compression is also a good test to do. Below minimum spec makes them hard starting cold.
 
cathead said:
The injectors were reinstalled and I ended up torquing them to about 70 foot pounds which seemed like plenty. It did start
a little better but still not what I would like to see.

I had an old hydraulic jack that was pretty much for parts so did some work on it to make an injector tester. It looks like
it will work so need to pull the injectors again and test them for atomizing spray and pressure. A fitting was needed to
go from 1/4 NPT to metric 12x1.5 so did a bit of machining and brazing to make one up. Just for fun I did the brazing with
some copper solid house wire #12 and some flux for brass. There wasn't much room to hold the middle of the fitting
so I drilled out a 1/2x13 nut to half inch and brazed it to the middle of the fitting using the copper wire. View attachment 397429
Brazing the nut on to the fitting was a lot easier than machining down one solid piece. It's not something I will use a lot of anyway.

View attachment 397432
After a little plumbing, it was ready to test.

View attachment 397434
Here the gauge is reading 1800+ PSI. I think the pop off pressure is supposed to be 1700PSI on these pintle injectors
so it should work to test them and add some shims if required.


It's another cold day about 10 below zero F and snowing to boot. Visibility is about a quarter mile or so at present. I don't
have much else going on today so might as well get on with it and pull the injectors again. Thanks for following along.:encourage:
Click to expand...

Good idea on the injector tester! But 10 below zero....... That's too darn cold !!
 
Oh man... it was only 16° here this morning. The sun is out bright now, it feels good but probably still only in the low 20s.

Tim
 
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